Application Note 1764 Author: Dan Goodhew ISL21090XXEV1Z User’s Guide Introduction ISL21090XXEV1Z Board The ISL21090XXEV1Z evaluation board is designed to measure the performance of the high precision ISL21090 voltage reference. The reference has a wide input voltage range from the individual threshold voltage to 36V and an initial accuracy of 0.02% to 0.035%. The voltage noise of 1µVP-P in the 0.1Hz to 10Hz range (1.25V option) and maximum output voltage temperature coefficient of 7 ppm/°C make the ISL21090 ideal for high end applications. The schematic of the evaluation board is shown in Figure 5. The ISL21090XXEV1Z contains the ISL21090 voltage reference (U1), input decoupling capacitors (C1, C2), a compensation capacitor (C5), and a load capacitor (C3). The evaluation board includes voltage input test points (VIN and GND) for a power supply input, as well as a pair of test points for the output (VOUT and GND). Additionally, a jumperable R-C damper network can connectL to VOUT (J1), and R2 accepts surface mount or through-hole style resistors for output load testing. The power supply leads attach to TP1 and TP2 (VIN, GND). The output is measured at test points TP3 and TP4 (VOUT, GND), and is best measured with a high quality voltmeter. The R-C damper network is populated and can be connected to the reference output by adding a shunt to the R-C jumper (J1). The damper network improves stability by reducing transient load ringing with high value (>0.47µF) capacitors. TABLE 2. COMPONENTS PARTS LIST DEVICE # VALUE Reference Documents C1 10µF Bypass Capacitor • ISL21090 Datasheet FN6993 C2 0.01µF Bypass Capacitor C3 0.1µF Load Capacitor C4 10µF Damper Capacitor C5 1nF R1 2.21kΩ R2 DNP U1 ISL21090 J1 DNP TABLE 1. ORDERING INFORMATION BOARD NUMBER OUTPUT VOLTAGE (V) TYPE ISL2109012EV1Z 1.25 Evaluation Board ISL2109025EV1Z 2.5 Evaluation Board ISL2109050EV1Z 5.0 Evaluation Board ISL2109075EVAL1Z 7.5 Evaluation Board DESCRIPTION Compensation Capacitor Damper Resistor Optional Load Resistor SOIC 8-Pin Package Damper Jumper FIGURE 1. VOLTAGE REFERENCE EVALUATION BOARD February 25, 2013 AN1764.1 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2012, 2013. All Rights Reserved Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. Application Note 1764 Voltage Reference Evaluation Board Layout FIGURE 2. TOP COMPONENTS FIGURE 3. BOTTOM LAYER ISL21090XXEV1Z FIGURE 4. ASSEMBLY DRAWING Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 2 AN1764.1 February 25, 2013 ISL21090XXEV1Z Schematic VIN TP3 TP1 3 1 2 4 C5 8 SOIC8 GENERIC 3 PACK 7 7 4 5 U1 2 1000pF 0.1µF 10µF C1 8 1 3 C2 GND 1 6 6 TP4 J1 2 5 R1 C4 C3 0.1µF DNP P1 P2 FIGURE 5. SCHEMATIC Application Note 1764 RC LOAD R2 2.21kΩ TP2 VOUT 10µF GND AN1764.1 February 25, 2013